Coolant is supplied in computer numerically controlled machines for various purposes. Typically, the coolant, which is an oil, an aqueous emulsion, or other liquid, is introduced under pressure via a nozzle. Grinding operations in general require adequate coolant at the point of contact between workpiece and the grinding wheel. In such operations, coolant typically is directed under pressure at the grinding wheel or workpiece or at the point of contact between the workpiece and wheel. The workpiece may itself be a cutting tool that is reground in the grinding operation or may be a functional part. In other operations, such as milling, coolant likewise may be applied to the workpiece or the tool, or applied at the tool-workpiece interface (point of contact). Also, the cooling fluid may be applied during or after a machine operation as a cleaning spray to wash away swarf.
The prior art has provided machines that include coolant nozzles, which, in many cases, are proximate the chuck of the machine tool. With typical coolant nozzle placement, it can be difficult to control and properly direct the coolant. This can cause difficulties. For instance, in a grinding operation it is typical for the coolant to be applied to the grinding wheel, which spins and which tends to throw off the coolant via centrifugal forces. It is sometimes desirable to maintain a constant time to interface, or time between the initial contact of the coolant with the grinding wheel and the time the coolant on the wheel reaches the interface between the wheel and workpiece. The grinding wheel often erodes during a grinding operation, and the ground dimension of the workpiece can decrease, thus requiring adjustment to the coolant nozzle if a constant time-to-interface is desired. In other circumstances, it may be desirable to maintain a constant contact angle, or rotational angle between the point of contact of the coolant on the workpiece or tool and the point of contact at the workpiece interface. Again, it can be difficult to maintain a constant contact angle, particularly if the size of the tool or of the workpiece changes, or as the position of the workpiece is varied.
U.S. Pat. Nos. 6,772,042 B1 (assigned to Dimensional Control, Inc.) and 6,666,748 B2 (assigned to Makino Milling Machines Co., Ltd.) purport to provide servo-controlled programmable coolant nozzles that are used to direct coolant to grinding wheel. The heretofore described servo-controlled coolant nozzle and programmable coolant nozzle of the prior art require special machine modifications. Generally, it is desired to provide in some embodiments a coolant nozzle arrangement and in some embodiments a method that differs from the foregoing.